Safety-paper.



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MESNEASSIGNMJENTS, TC t Tl. CCRTCRATTCTT C ILJLTITCIS.

To all whom itmay concern:

Be it ,known that T, Ennns'r EMIL SCHMIDT, a citizen-of the United States, residing at Boston, in the county of Sufiolk and State of Massachusetts, have invented new and useful Improvements in SafetylPaper, of which the following is a specification.

This invention relates to paper used for checks, notes, wills, deeds, etc., and has for its object to prevent successful fraudulent alteration of matter written on such paper with commercial fluid ink, the invention be ing an improvement on the safety paper disclosed by Letters Patent of the United States, No. 1,217,076, dated Feb. 2, 1917.

The paper disclosed by said patent is treated with an agent, or composition, adapted to chemically combine with the essential ingredients of commercial writin ink in rendering matter written with said ink indelible either by the acid and alkaline ink eradicators usually employed to remove commercial ink from paper, or by the abrasive action of a mechanical eraser.

The paper forming the subject of the present invention-is treated while dry with a similar agent, or composition, for the above-mentioned purpose, which is printed on the dry paper said composition also including an ingredient adapted to combine with acid and alkaline ink eradicators in indelibly staining the entire area of the paper to which such eradicators are applied. The composition preferably further includes a sizing ingredient, which imparts body to the composition, and thus enables it to be applied in narrow spaced-apart lines of any desired configuration by a printing operation to the surface of dry paper, to form any desired desi thereon.

T have used with satisfactory results the following formula Sodium ferrocyanid, ten ounces. (As an equivalent, I may use instead the same quantity of potassium ferrocyanid.)

Sodium iodid, twelve ounces. (As an equivalent, ll may use instead the same quantity of potassium iodid.)

Sizing composition, compounded as stated below, sixteen ounces.

Glycerin,one ounce.

Ux-gall, one ounce.

Water added to the above in sufiicient quantity to form one gallon of composition.

Specification of Letters Patent. I

ERNEST. EMU SCHMIDT, CF ECSTCN, MASSACHUSETTS, ASSIGNOR, JET lDmllJC'll 11 :EAMOUNT SAFETY PAPER 00., OF CHICAGO, TLTJTNCT,

SAFETY-PER.

Patented dune tlfi, Tfit,

Application filed February 6, 191?. Serial No. M63961.

The sizing composition is compounded as follows:

Tapioca flour, fifty pounds.

Caustic soda, three and one-half pounds.

Water, three hundred and fifty pounds.

The sizing composition should be well stirred or agitated for about one hour, to prepare it for use. The caustic soda dissolves such portions of the tapioca flour as are not readily soluble in water, and renders all portions of the flour soluble in water.

The complete composition containing the described ingredients in substantially the proportions above specified, should be stirred or agitated for about fifteen minutes, before application to the paper.

I prefer to add to the composition a neutralizing solution prepared by dissolving three and one-half pounds of muriatic acid, in twenty pounds of Water, a suitable quantity of the neutralizing solution for one gallon of the composition being twelve ounces.

The described composition is preferably applied as a surface coating to one side of a web of dry paper. The composition may be applied to form narrow slightly spaced apart lines, arranged to produce any desired design. For example, said lines may be parallel with each other to produce the efi'ect of fine ruling, or they may be more or less involved to produce a variety of designs.

The lines may be applied to the paper byany suitable means such as a ruling machine, or a suitably engraved roll receiving the composition from a supply roll partially immersed in a tank containing the composition. The smooth periphery of the engraved roll between the depressions formed by the sunken lines engraved thereon, may be kept clean by a doctor bar, pressed against it, and a web of paper drawn from a roll ma be fed over the engraved roll and pressed against the latter, so that the paper takes up the composition in the said depressions, as in plate printing. The paper after receiving the composition, should be conducted a suitable distance, without contact of the freshly printed surface with any support, to enable the composition to dry before the printed paper is re-rolled. The paper employed is sized paper such as is ordinarily employed for bank checks, etc. The ction of the ox-gall is to cut through the sizing of the dry paper on which the composition is printed, andincrease its porosity and permeability so that the composition and commercial writing-ink subsequently applied sink deeply into the paper, The iron in commercial writing-ink penetrating the paper, combines with an ingredient 0r ingredients of the composition to render the ink indelible. For example, if ferro-cyanid of sodium is an ingredient of the composition, this ingredient which has deeply penetrated the paper, combines with the iron of the ink and forms ferro-cyanid of iron, which is Prussian blue and is chemical proof.

After the paper has been coated with my improved safety composition, any attempt to remove the ink .with any of the well known chemica eradicators Wlll result in making the ink indelible. The ingredients in the eradicators, such as the acid and the alkali, which must be used alternately, in order that writing ink may be removed from paper, release a substance from the coating, which will combine with the iron of the ink to form Prussian blue. As an example, when my safety paper has been written upon with writing mk an acid is first used to soften the ink. If the alkali is first used, the ink cannot be removed successfully, but the brown iodin stain will be produced. There fore, to remove the ink the acid must first be used and just as soon as any acid is applied, the same at once combines with the iron in the ink and also combines with the ferro cyanids in the coating, producing ferro cyanid of iron. Thus an indelible ink is produced.

In addition to the above described reaction, when commercial eradicators are ap plied to my safety paper, the sodium iodid,

, or equivalent substance, is decomposed, re-

leasing free iodin which produces a stain upon the paper.

The starch size being an alkali, it is necessary'to break up the insoluble matter, and for this purpose caustic soda is employed. The chemicals of the safety material being of an acid nature, it is necessary to neutralize the sizing in order to mix them. After the caustic soda has been added to the tapioca sizing, the soda dissolves, rendering soluble all normally insoluble substances in the sizing. The acid is then added to neutralize the alkaline condition of the sizing, after which the other chemicals, which are of an acetic nature, are added.

I claim: I

' 1. A safety paper comprising a paper coated with a composition including ox-gall which renders the paper permeable by the composition, said composition containing ingredients capable of bein decomposed by acid and alkaline ink era icators to release substances which will respectively react to indelibly stain the paper, and to .render indelible commercial writing ink containing iron.

2. A safety paper comprising a paper coated with a composition containing-sodium or potassium ferrocyanid, sodium or potassium iodid, glycerin, ox-gall, tapioca flour, and caustic soda.

In testimony whereof I have affixed my signature.

ERNEST EllflL SCHMIDT. 

